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Hip: K. Gurusamy, M. J. Parker, and T. K. Rowlands The complications of displaced intracapsular fractures of the hip: THE EFFECT OF SCREW POSITIONING AND ANGULATION ON FRACTURE HEALING J Bone Joint Surg Br 2005; 87-B: 632-634 [Abstract] [Full text] [PDF]

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Electronic letters published:

Reply to Dr Dinah from Mr Parker

Martyn J Parker   (6 July 2005)

Reply to Dr Nithyananth from Mr Parker

Parker Martyn   (6 July 2005)

Is screw positioning really the most important factor?

Manasseh Nithyananth   (23 June 2005)

Is screw positioning really the most important factor?

Feroz Dinah   (17 June 2005)

Reply to Mr Todkar from the authors

Martyn Parker, Kurunchi Gurusamy and Tom Rowlands   (19 May 2005)

Is placement of screws the only cause of nonunion in fracture of the femoral neck?

Manoj Todkar   (12 May 2005)

Reply to Dr Dinah from Mr Parker 6 July 2005
Martyn J Parker, Orthopaedic Research Fellow Peterborough District Hospital, Peterborough, PE67NJ Send letter to journal: Re: Reply to Dr Dinah from Mr Parker mjparker{at}doctors.org.uk Martyn J Parker	Sir, I thank Dr Dinah for his interest in our article. There is no doubt that factors such as fracture reduction are of great importance in the outcome after reduction and fixation of intracapsular fractures. Many previous studies have documented the effects of fracture reduction, but few have mentioned the positioning of the implant. The results should be related to fracture reduction, but with the number of patients studied this becomes increasingly complicated. This study was intended purely to focus on positioning of the implant, and I agree that the small difference in positioning on the lateral radiograph is of questionable clinical significance, but it should be taken as a stimulus for future studies. This study also showed that we should end our obsession with the ‘parallelism’ of the screws. I am not sure how the results of this study relate to that of my previous study with two parallel Garden screws. Indeed, there was a suggestion that anterior placement of the Garden screws was associated with an increased risk of nonunion. For this implant the screws were positioned with a jig, and if one screw was anterior then the other generally also was and the spread of the screws (which I feel is important in achieving good hold of the bone) was not achieved. M. PARKER, FRCS Peterborough District Hospital, Peterborough, UK.
Reply to Dr Nithyananth from Mr Parker 6 July 2005
Parker Martyn, Orthopaedic Research Fellow Peterborough District Hospital Send letter to journal: Re: Reply to Dr Nithyananth from Mr Parker mjparker{at}doctors.org.uk Parker Martyn	Sir, I thank Dr Nithyananth for his comments. It is certainly correct that all such radiographs should ideally be taken at an internal rotation of 10° to 15° of the hip in order to minimise errors. I cannot guarantee that this was the case for all patients in this study but have no evidence to suggest that the lack of this standardisation resulted in any difference in the interpretation of the data. Future studies on the positioning of the implant should of course strive to achieve standard positioning of the limb, but unfortunately this is often not easy to achieve in the clinical setting. M. PARKER, FRCS Peterborough District Hospital, Peterborough, UK.
Is screw positioning really the most important factor? 23 June 2005
Manasseh Nithyananth, Lecturer Department of Orthopaedics, Christian Medical College, Vellore Send letter to journal: Re: Is screw positioning really the most important factor? nmanasseh001{at}yahoo.co.in Manasseh Nithyananth	Sir, I read this article with great interest. In addition to the questions raised in the earlier letters I would like to point out that intra-operative radiographic images have been used to effect various measurements. Very often the intra-operative radiographic images do not provide full details.1 Unless all the images were obtained by standardised means, some of the differences in measurement could be attributed to different positioning of the limb. Internal rotation of 15° is recommended to remove the beam parallax in anteroposterior imaging.1 N. NITHYANANTH Christian Medical College Vellore, India. 1. Robert WB, James DH. Fractures in Adults. Vol. 2, Fourth ed. Philadelphia: Lippincott Williams and Wilkins 2001:1584-97.
Is screw positioning really the most important factor? 17 June 2005
Feroz Dinah, SpR St George's Hospital, London UK Send letter to journal: Re: Is screw positioning really the most important factor? feroz72{at}hotmail.com Feroz Dinah	Sir, I read this article with interest. However, the authors seem to have overlooked the fact that inadequate fixation is not the only factor known to affect the healing of fractures. In fact, studies have shown that poor reduction is another important predictor of nonunion.1-3 As such, the conclusion that a wide antero-posterior spread of screws is desirable needs to be qualified by the adequacy of the reduction of the fracture. In Table I, the difference in antero-posterior spread of screws between union and nonunion subgroups was about 3%. In a femoral head of 50mm diameter this would be equivalent to an actual difference of about 1.5mm, and the observed difference on the intra-operative radiograph would depend on the magnification. This raises the question of whether the calculated difference is purely of statistical rather than clinical significance. Interestingly, a previous study by Parker found that a wider antero-posterior spread of screws was associated with a higher rate of non-union of these fractures.3 F. DINAH, MRCS(Eng) St George’s Hospital, London, UK. 1. Weinrobe M, Stankewich CJ, Mueller B, Tencer AF. Predicting the mechanical outcome of femoral neck fractures fixed with cancellous screws: an in vivo study. J Orthop Trauma 1998;12:27-36. 2. Alberts KA, Jervaeus J. Factors predisposing to healing complications after internal fixation of femoral neck fracture: a stepwise logistic regression analysis. Clin Orthop Relat Res 1990;(257):129-33. 3. Parker MJ. Parallel Garden screws for intracapsular femoral fractures. Injury 1994;25:383-5.
Reply to Mr Todkar from the authors 19 May 2005
Martyn Parker , Kurunchi Gurusamy and Tom Rowlands Send letter to journal: Re: Reply to Mr Todkar from the authors mjparker{at}doctors.org.uk Martyn Parker, et al.	Sir, We thank Mr Todkar for his interest in our article. Indeed, there are numerous factors which influence the risk of fracture-healing complications for intracapsular fractures. Some of these factors may, however, only be associated with fracture-healing complications, rather than being causal. A study of all these factors would be extremely difficult to undertake. The study by Barnes et al1 addressed some of these factors, but 23 pages of the Journal of Bone and Joint Surgery [Br] were required to report the findings. The reader should not use the figures from our article to calculate the incidence of nonunion for displaced intracapsular fractures (39%). As stated in our article, this is not a consecutive series of patients. Overall, 591 patients were treated at our unit for a non-pathological displaced intracapsular fracture during the period of study. This gives a rate of nonunion of 26%. Regarding the parallel insertion of screws, one should differentiate between the methods previously described such as crossed Garden screws, in which there was an attempt to prevent fracture collapse by placing the screws at an angle of 60° to 90°, and this study where the mean angle between screws was 5°. We feel that a minor degree of angulation for screws in the osteoporotic bone of the femoral neck would not have much effect in preventing collapse of the fracture. As our study shows, the separation of screws into different areas of the bone is more effective in reducing the risk of nonunion than is parallelism. M. PARKER, MD, FRCS T. ROWLANDS, MBBCh, MRCS (Eng) Peterborough District Hospital Peterborough, UK. K. GURUSAMY, MBBS, MRCS Ed QUQM Hospital Margate, UK. 1. Barnes R, Brown JT, Garden RS, Nicoll EA. Subcapital fractures of the femur: a prospective review. J Bone Joint Surg [Br] 1976;58-B:2-24.
Is placement of screws the only cause of nonunion in fracture of the femoral neck? 12 May 2005
Manoj Todkar, Orthopaedic Trainee Nuffield Orthopaedic Centre Send letter to journal: Re: Is placement of screws the only cause of nonunion in fracture of the femoral neck? mtodkar{at}hotmail.com Manoj Todkar	Sir, I read this article with great interest. In this study the only factor that the authors consider for cases of nonunion is the position of cannulated screws on radiographs. The rate of nonunion is approximately 39% in this series. However, it is well established that a number of other factors are also responsible for nonunion, for example comminution at fracture site, osteoporosis, physiological age of patient, apex tip distance of screws, and delay between occurrence of fracture and fixation.1 None of these factors were considered in this study. The authors state that they feel that mechanical failure of fixation should be blamed for most nonunions, which is a generalisation. In fact, in most cases of nonunion implant failure is secondary to biological failure. Their other conclusion is that the degree of angulation between the screws had no measurable effect on the risk of nonunion. It is well known that collapse at the fracture site will not occur unless the screws are parallel.2,3 Lack of parallelity between the screws was one of the important factors in the failure of Gardens screws placed at 90° used for fixation of these fractures.4 M. TODKAR Nuffield Orthopaedic Centre, Oxford, UK. 1. Parker MJ. Prediction of fracture union after internal fixation of intracapsular femoral neck fractures. Injury 1994;25 Suppl 2:B3-6. Related Articles 2. Rehnberg L, Olerud C. Fixation of femoral neck fractures: comparison of Uppsala and Von Bahr screws. Acta Orthop Scand 1989;60:579–84. 3. Lagerby M, Asplund S, Ringqvist I. Cannulated screws for fixation of femoral neck fractures: no difference between Uppsala and Richards screws in a randomized prospective study of 268 cases. Acta Orthop Scand 1998;69:387–91 4. Parker MJ, Porter KM, Eastwood DM, Schembi Wismayer M, Bernard AA. Intracapsular fractures of the neck of femur. Parallel or crossed garden screws? J Bone Joint Surg [Br] 1991;73-B:826-7.